The present invention relates to a refrigerant circuit, in particular a heat pump circuit, having dual-stage evaporation.
In heat pump circuits which are used in vehicles, the risk of freezing of the “ambient heat exchanger” or evaporator is a central problem. Freezing of the ambient heat exchanger is intended to be prevented since otherwise the power of the heat pump would significantly decrease.
An object of the invention is to provide a refrigerant circuit or heat pump circuit which is suitable for use in a vehicle and in which the risk of freezing of the ambient heat exchanger(s) of the refrigerant circuit is minimized.
This and other objects are achieved by a refrigerant circuit for vehicles, in particular a heat pump circuit for vehicles, which, when viewed in the flow direction of the refrigerant, has the following components:
a refrigerant compressor,
a condenser or gas cooler,
a first refrigerant/air heat exchanger which acts as a sub-cooler and via which the refrigerant discharges heat to the ambient air,
a first expansion member,
a second refrigerant/air heat exchanger via which the refrigerant absorbs heat from the ambient air,
a second expansion member, and
a third refrigerant/air heat exchanger via which the refrigerant heat absorbs heat from the ambient air.
A central aspect of the invention involves the third refrigerant/air heat exchanger, which is particularly susceptible to freezing and via which the refrigerant is intended to absorb heat from the environment, being arranged with respect to the first refrigerant/air heat exchanger in such a manner that it is thereby protected from freezing. To this end, the first refrigerant/air heat exchanger is arranged in such a manner that heated air which is discharged by the first refrigerant/air heat exchanger (sub-cooler) flows against, through or around the third refrigerant/air heat exchanger which is at risk of freezing.
According to an aspect of the invention, the refrigerant circuit is arranged in a vehicle. When viewed in the travel direction of the vehicle, the first refrigerant/air heat exchanger (sub-cooler) is arranged upstream of the third refrigerant/air heat exchanger which is particularly at risk of freezing. In other words, the third refrigerant/air heat exchanger which is particularly at risk of freezing is arranged downstream with respect to the flow direction of the ambient air (travel wind), that is to say, with respect to the first refrigerant/air heat exchanger, whereby, as already mentioned above, it is possible for the air or travel wind which is discharged by the first refrigerant/air heat exchanger to flow against or through the third refrigerant/air heat exchanger.
According to an aspect of the invention, the second refrigerant/air heat exchanger is arranged upstream of the first refrigerant/air heat exchanger (sub-cooler) when viewed in the travel direction of the vehicle.
The three refrigerant/air heat exchangers are thus arranged in a row one behind the other in the flow direction of the air or the travel wind.
In particular, there may be provision for the first refrigerant/air heat exchanger (sub-cooler) and the second refrigerant/air heat exchanger and the third refrigerant/air heat exchanger to be arranged, when viewed in the travel direction of the vehicle, in front of a drive motor, in particular in front of an internal combustion engine in the engine compartment of the vehicle.
The first and/or second expansion member may be purely mechanically controlled, thermostatic expansion members which are very cost-effective. Such purely mechanically controlled, thermostatic expansion members control “independently”, that is to say, do not require any electronic control system or the like.
Alternatively, the first and/or the second expansion member could naturally also be constructed as an electrically controlled or regulated expansion member.
The condenser or gas cooler may be a refrigerant/air heat exchanger, that is to say, a heat exchanger via which the compressed refrigerant discharges heat to the ambient air.
Alternatively, the condenser or gas cooler could also be a refrigerant/fluid heat exchanger via which the refrigerant discharges heat, for example, to a coolant circuit of the vehicle, in particular to a coolant circuit of the internal combustion engine.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawing.